1. Field of the Invention
The present invention generally relates to methods and apparatus for stimulating certain areas of the brain to treat mood disorders by modulation of electrical activity of neural tissue in the selected area of the brain.
2. Description of Related Art
Recent developments in psychobiology and psychopharmacology have provided considerable evidence that major depressive disorder and bipolar depression are biological rather than psychological diseases. The conclusion that depression has a biological basis is also supported by numerous electrophysiological and endocrine studies. Deficiency of brain neurotransmitters has been associated with depression. In particular, abnormally low concentrations of the neurotransmitter serotonin and its metabolites and norepinephrine have been found in depressed patients. Several serotonin uptake inhibitors, which increase the amount of serotonin at the synapse have been shown to be effective antidepressants. Increased activity of the vagus nerve has been postulated to be associated with release of increased amounts of serotonin and norepinephrine in the brain.
U.S. Pat. No. 5,299,569 (Cyberonics, Inc.) discloses methods and devices for treating and controlling certain neuropsychiatric disorders by selective stimulation of the vagus nerve. A neurostimulator which is preferably, but not necessarily, implantable selectively applies the therapy to treat the specific neuropsychiatric disorder such as schizophrenia, depression, borderline personality disorder, or other related disorder. The therapy is delivered in a manner to stimulate or modulate the vagal activity of the patient in a predetermined manner to treat and relieve the symptoms of the disorder, although it may not be effective in alleviating the underlying root cause of the disorder. The neurostimulator is programmed by the attending physician to generate a pulsed electrical signal that provides the desired therapeutic modality for treatment.
U.S. Pat. No. 6,622,047 (Cyberonics, Inc.) discloses selective modulation of vagus nerve electrical activity using a neurostimulator device that may be implantable, or used external to the body with only a small portion of the circuitry implanted or with only the nerve electrode(s) and associated lead(s) implanted percutaneously in the body, to treat neuropsychiatric disorders including depression.
U.S. Pat. Nos. 6,418,344 and 6,609,030 (ElectroCore Techniques, LLC) describe methods for treating psychiatric diseases such as anxiety disorders and affective disorders by electrical or chemical neuromodulation of regions within the orbitofrontal cerebral cortex and the dorsomedial nucleus of the thalamus.
U.S. Patent Application Publication No. 2005/0027284 (Advanced Neuromodulation Systems, Inc.) describes electrical and/or chemical stimulation and transcranial magnetic stimulation applied to certain areas of the brain that exhibit altered activity in patients, relative to psychiatrically normal control subjects. Such stimulation is said to be produced by electrical stimulation, an excitatory neurotransmitter agonist (norepinephrine), an inhibitory neurotransmitter antagonist, and/or a medication (i.e., fluoxetine, trazodone) that increases the level of an excitatory neurotransmitter. An effective treatment site is said to be a subcallosal area including subgenual cingulate area, subcallosal gyrus area, ventral/medial prefrontal cortex area, ventral/medial white matter, Brodmann area 24, Brodmann area 25, and/or Brodmann area 10.
U.S. Pat. Nos. 6,263,237 and 6,128,537 (Medtronic, Inc.) describe certain techniques for treating an anxiety disorder by means of an implantable signal generator and electrode and/or an implantable pump and catheter, wherein the electrode and/or catheter are surgically implanted in the brain. The type of drugs administered into the brain depends on the specific location of delivery and the desired action on the neurons at that location. Electrical stimulation of amygdala, dorsal raphe nucleus, septum, frontal cortex, anterior nucleus of thalamus, mammillary body, parenchyma, anterior limb of the internal capsule, head of the caudate nucleus, cingulum fibers, cingulate gyrus, dorsal medial nucleus of thalamus and locus ceruleus, are described.
U.S. Pat. No. 6,176,242 (Medtronic, Inc.) similarly describes techniques for treating depression or manic depression by deep brain stimulation at certain sites in the brain.
U.S. Pat. No. 6,708,064 (Rezai) describes a method for treating neurological conditions by proper placement of a probe and sensing certain areas of the brain, especially the intralaminar nuclei, to affect psychiatric disorders.
Alternative ways to treat patients suffering from severe or life threatening depression or other mood disorder that is not sufficiently responsive to conventional therapies are needed.